Molecular orientation controlled by light is useful for many applications such as display and information storage. Small molecular size permits high spatial resolution. Holographic data storage is an attractive technique because of its extremely high capacity, fast data access, and exceptionally fast data transfer rate.
In holographic storage, information data is recorded as gratings, as either refractive index modulation or absorptive index modulation, in the optical recording medium. Therefore, the physical characteristics of the recording medium are important for the performance of the holographic storage system. Organic materials are receiving much attention for this application due to inexpensive cost, easy preparation of large area optical films and possibility of high diffraction efficiency. However, the stored information can be easily erased by reading with a wavelength close to the wavelength used to write the information. Nonvolatile holographic storage is achieved using inorganic crystals doped with two centers such as Lithium Niobate doubly doped with iron and manganese. The use of inorganic crystals is disadvantageous due to high cost, slow response and difficulty in preparation of thin films with a large area.
There still remains a need for providing nonvolatile optical storage systems.